1. Field of the Invention
The present invention relates to a cleaning device for cleaning the operating components of a playing and/or recording video unit.
Such video units may be either used for playing from and/or recording onto a tape in a cassette. The video unit in general has a receiving area for a video tape cassette. A rotating drum with a recording/playback video head hereinafter referred to as a recording head is mounted in the receiving area over which the tape is passed and which either scans from the tape or records onto the tape. Guide means, usually rollers on pivotal arms, are provided in the cassette receiving area to move the tape outwardly from the cassette towards and partly around the drum. In general, a capstan and pinch roller arrangement is provided which controls the tape speed onto or from a spool in a cassette which is driven by a corresponding spindle in the video unit. Sound and erase heads are also provided in the tape path. The problem with such video units is that in general the drum and recording video head, guide means, capstan and pinch roller, and other components in the tape path, usually collect dirt deposits. This may be dust, particles from the tapes or any other undesirable foreign matter. Once the build-up of dirt exceeds certain limits, the video unit fails to function effectively. One of the major problems with dirt collecting on the capstan and pinch roller is that this dirt can effect tracking and playing speed of the video tape. Furthermore, this dirt can readily easily be transferred by the tape onto the sound and video heads, thereby affecting sound and picture quality, and can damage the tape. It is therefore essential that all components in the tape path are kept as free of any dirt deposits as possible.
2. Discussion of the Prior Art
Cleaning devices to achieve this are known. However, such devices have been found in the past to suffer from various disadvantages. In general, these known devices comprise a cassette housing which is substantially similar to a video tape cassette, but instead of having a magnetic tape wound onto the spools, a cleaning tape is provided. The cassette is placed in the receiving area of the video unit, and functions as an ordinary video tape cassette, with the exception that as the cleaning tape is drawn across the components in the tape path the action of the tape on the components cleans the components. The cleaning action is further assisted by applying a cleaning solution to the tape.
By virtue of the fact that the cleaning tape is of similar width to a magnetic video tape only the area of the components in contact with a normal magnetic video tape is cleaned. Thus, any dirt deposits outside these areas are not removed. This is a particularly major problem in that most dirt deposits build up on the components in the tape path on either side of the path along which the tape passes. These deposits eventually enter the path of the tape, and are carried along and deposited on the video and sound head and other components. The fact that most dirt deposits accumulate on each side of the tape path is caused by the action of the video tape constantly passing over the components, and this tends to keep the tape path relatively clean. However, dirt tends to be squeezed out by the tape and collects as a deposit on each side of the tape path. This is a particular problem on the drum. As this dirt deposit accumulates, in general,bits of dirt become detached and fall into the tape path, and are thus carried along and deposited, usually on either the video head or the sound head. This immediately either reduces considerably the efficiency with which the video can operate, or in many cases causes major distortion in both the picture and sound of the device.
Thus, because known cleaning devices clean by the action of a cleaning tape passing over the components, and since the cleaning tape only cleans the tape path of a normal video magnetic tape, known cleaning devices are incapable of removing dirt deposits which build up on the components and in particular the drum, on either side of the tape path. Furthermore, in certain cases it has been found that because of incorrect tension in the cleaning tape, the tape may bear lightly on part of the dirt build-up adjacent the tape path. It has been found that this action is not sufficient to remove such dirt, but in many cases may loosen it sufficiently that the loosened dirt may subsequently fall into the tape path when a video tape is being played. In fact, it has been found on many occasions that shortly after cleaning with known cleaning devices, dirt deposits fall into the tape path and these may be deposited on the sound or video heads.
A further problem with known cleaning devices is that by virtue of the fact that the cleaning tape is usually of a textile material, the frictional drag over the components and in particular over the drum is greater than the frictional drag between a normal magnetic video tape and the drum. This leads to excess loading on the drive mechanism, and in particular the electric motor or motors driving the various components. In certain cases it has been known for electric motors to burn out while the video unit was being cleaned with a tape type cassette cleaning device. In fact, this problem may even be amplified when a liquid cleaning solution is sprayed onto the tape, since in general, it has been found that the cleaning solution tends to further increase the friction drag between the cleaning tape and the drum.
A further problem with the known tape type cassette cleaning devices is that by virtue of the fact that the cleaning is carried out by the action of a cleaning tape passing over the components, only the surfaces in contact with the tape are cleaned. For example, in many cases grooves are formed in the outer periphery of the drum, and it is impossible for the cleaning tape to clean such grooves.
There is therefore a need for a cleaning device which cleans the components, and in particular the drum in which the video heads are mounted more efficiently than cleaning devices known heretofore.